Molecular biologists have identified the chromosomal defects in a large number of human hereditary diseases, raising the prospects for cures using gene therapy. This emerging branch of medicine aims to correct genetic defects by transferring cloned and functionally active genes into the afflicted cells. Several systems and polymers suitable for the delivery of polynucleotides are known in the art. In addition, gene therapy may be useful to deliver therapeutic genes to treat various acquired and infectious diseases, autoimmune diseases and cancer.
Despite the usefulness of polynucleotide delivery systems, such systems are metastable and typically exhibit a decrease in activity when left in solution for longer than a few hours. For example, conventional cationic-lipid mediated gene transfer requires that the plasmid DNA and the cationic lipid be separately maintained and only mixed immediately prior to the gene transfer. Current attempts to stabilize polynucleotide complexes comprise speed-vac or precipitation methods, but they do not maintain activity over suitable time periods. Attempts to store polynucleotides in salt solutions lead to a loss of supercoil structure. If gene therapy protocols are to become widely used it will be necessary to have a stable and reproducible system for maintaining activity. This is of particular importance to pharmaceutical and commercial uses. Accordingly, there remains a need for means to stably maintain polynucleotide compositions for extended periods of time. The present invention satisfies this and other needs.